Printer including cartridge mounted interchangeable read only memory

ABSTRACT

A printer with a main body having a printing head, motors, a plurality of circuits driving the printing head and the motors, a processor and a random access memory. The printer also includes a cartridge for containing memory devices for storing the data for at least one character font set and for storing the printing operation control program. A connector removably connects the cartridge mechanically and electrically to the main body of the printer. As a result, the print operation control program and character font set data can be selectively set by connecting an appropriate cartridge to the main body of the printer.

This is a continuation of application Ser. No. 06/748,253, filed June24, 1985, now abandoned.

BACKGROUND OF THE INVENTION

The invention is generally directed to a printer and in particular to aprinter in which the print control functions and type fonts can bechanged in accordance with the functioning of a computer or likeapparatus (host machine).

The development of various types of computers has resulted in a vareityof methods of controlling a printer by the host computer. The methodsdiffer from one another in, for example, the style of characters,symbols or dot patterns and horizontal or vertical print positioncontrol. As a result, it is often necessary to change the printercontrol program in order to use the printer with a host computerdesigned to operate utilizing a different control method.

Conventional printers contain a print head driving circuit, a carriage(CR) motor driving circuit, a line feed (LF) motor driving circuit, amicroprocessing unit (MPU) for controlling the overall operation of theprinter, a random access memory (RAM), a control read-only memory (ROM)for storing instruction data for the MPU and controlling the printer, acharacter read-only memory (ROM) for storing the printing characters andan interface for connecting the printer to the host computer. All ofthese components are traditionally mounted on one or more fixed circuitboards. A change in any of these circuits requires a change in the boardor boards. This is a major and expensive change. Because of thecomplexity of the circuits utilized in the printer, the development andimplementation of a new program for a printer is often time consumingand expensive.

As a result of these problems, it has also been necessary to utilizeseveral different production lines to produce printers with differentspecifications adapted to various types of printing control methods.Consequently, there are often production lines which are not being fullyutilized. The difficulties raised by the changes in the specificationsfor the printers has also caused a problem in inventory control. Inparticular, some printers with certain specifications which are indemand tend to sell well and are in short supply while printers withother specifications which are not in the same demand are overstocked.

Accordingly, there is a need to provide a printer which can have itsspecifications easily changed, thereby both simplifying the productionprocess and reducing inventory control problems.

SUMMARY OF THE INVENTION

The invention is generally directed to a printer including a main bodywith a printing head, motors, a plurality of circuits for driving theprinting head and the motors, a microprocessor unit and a random accessmemory. A cartridge contains memory devices for storing data associatedwith at least one character font set and for controlling the printingoperation of the printer. A connector for removably connecting thecartridge mechanically and electrically to the main body of the printeris provided. As a result, the print operation control and characterfonts can be selectively set by connecting an appropriate cartridge.Likewise, the print operation control and character fonts can be changedby connecting a different cartridge to the main body.

Accordingly, it is an object of the invention to provide an improvedprinter.

Another object of the invention is to provide an improved printer, thespecifications of which can be easily changed.

A further object of the invention is to provide an improved printerwhich allows for the adaption of a single printer to a variety of hostmachines with different print operation control systems by storing theprint operation control program and character font information on aremovably attachable cartridge which fits into and is electricallycoupled to the main body of the printer.

Still another object of the invention is to provide a printer with aremovable cartridge for containing printing control and character ROMswhich can be changed to suit different host machines to which theprinter is connected.

Yet a further object of the invention is to provide an improved printerwith a cartridge containing the character font information and printcontroller program so that a single production line can be provided foreach type or model of printer, regardless of the difference inspecification.

Still another object of the invention is to provide a printer with aremovable cartridge for storing character font information andcontrolling the printing operation which also provides an interface withthe host computer.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction,combinations of elements, and arrangements of parts which will beexemplified in the constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a block diagram of a conventional printer;

FIG. 2 is a block diagram of a printer constructed in accordance withthe instant invention;

FIG. 3 is a schematic view of a cartridge used in the printerconstructed in accordance with the invention;

FIG. 4 is an exploded schematic view of a printer constructed inaccordance with the invention showing the cartridge in a position to beconnected to the main body of the printer;

FIG. 5 is an exploded, partially cut-away perspective view of the mannerin which a cartridge is connected to the main body of a printerconstructed in accordance with another embodiment of the invention;

FIG. 6 is a schematic circuit diagram showing the electrical connectionsbetween the cartridge and the main body of the printer constructed inaccordance with the invention; and

FIG. 7 is a flow-chart diagram depicting the operation of the printerconstructed in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is made to FIG. 1 wherein a conventional printer, generallyindicated at 100 is depicted. Printer 100 includes a print head 1, acarriage motor (CR) 2, a line feed (LF) motor 3, a print head drivingcircuit 4, a CR driving circuit 5, a LF driving circuit 6, amicroprocessor unit (MPU) 7 for controlling the overall operation of theprinter 100, a random access memory (RAM) 8, a control read-only memory(ROM) 9 for storing instruction data for the MPU 7 and controlling theprinter 100, a character read-only memory (ROM) 10 for storing theprinting character data and an interface 11 for connecting the printer100 with a host computer (not shown). The various components are mountedon one or more fixed circuit boards 12. Any change in the circuitsrequires a change in the board or boards 12. This is a large andexpensive change and the circuits are so complex that considerable timeand expense is involved in developing a new program.

Reference is next made to FIG. 2 wherein a printer, generally indicatedas 200 constructed in accordance with a preferred embodiment of theinvention is depicted. Printer 200 includes a circuit board 30 in acartridge 31 (FIG. 3) which is separate from a circuit board 20 locatedin the main body 40 (FIG. 4) of printer 200. Board 20 includes a printhead driving circuit 4 for driving print head 1, a CR motor drivingcircuit 5 for controlling the operation of CR motor 2 and a LF motordriving circuit 6 for controlling the operation of LF motor 3. Main bodyboard 20 also contains a microprocessor unit (MPU) 7 and a random accessmemory (RAM) 8. The elements on board 20 as well as print head 1, CRmotor 2 and LF motor 3 are contained in the main body of the printer 200(FIG. 4).

Board 30 includes a control read-only memory (ROM) 9 for storing theorder by which print head driving circuit 4, CR motor driving circuit 5and LF motor driving circuit 6 are controlled. A character ROM 10 storesa variety of patterns of character styles in various fonts. An interface11, such as the RS232C interface is also present in cartridge board 30and is used to connect the cartridge 31 to the host machine 72 with aplurality of electrical lines 32 (FIG. 3).

Control and character ROMs 9 and 10 can be configured as either a singleROM or as two separate ROMs. If two separate ROMs are used it is oftennecessary to provide a circuit to select between the appropriate ROMs atdifferent times during the printing process. Character ROM 10 is notlimited to a single character font, but may store a plurality of fontssuch as Ming, Gothic, and Boldface types.

Interface 11 is not limited to the RS 232C standard but may be adaptedfor different specifications, such IEEE 488 or GP-IV. It is alsopossible for interface 11 to be configured as a serial or parallelinterface.

Reference is made to FIGS. 3 and 4 wherein the manner in which cartridge31 is connected to main body 40 of printer 200 is depicted. Board 30 hasa connector 33 which connects to the main body 40 (FIG. 4) of theprinter 200. Cartridge 31 has an opening 34 through which connector 33projects. Main body 40 has a cartridge support 41 adapted to receivecartridge 31 or a portion thereof. Cartridge support 41 engages withconnector 33. Although FIG. 4 shows cartridge support 41 and opening 410in the rear of printer main body 40, the opening 410 and support 41 canalso be positioned at the front, sides, top or bottom of the main body40. FIG. 4 also schematically depicts print head 1 and a platen 42.

Reference is next made to FIG. 5 wherein another embodiment of thecartridge-printer connection constructed in accordance with theinvention is depicted. A ROM 50 for storing both a print control programand at least one character font is connected to board 30' by an ICsocket 51. Board 30' also includes an IC 52 for reading ROM 50. Board 30has a male connector 53 which is adapted to engage with a femaleconnector 54 on the main body 40 of the printer 200 to provide both amechanical and electrical connection between cartridge 31' and main body40 of the printer 200. Main body 40 has an upper support base 55 and alower base 56 below upper base 55 for supporting cartridge 31'. Bases 55and 56 are connected to each other by male and female connectors 57 and58 extending therebetween and adapted to engage each other. Main body 40is also provided with a connector 59 for an external interface. Two ICs60 and 61 are also provided on base 56. ICs 60 and 61 may be used toimplement the external interface or for other purposes.

In the device of FIG. 5 the interface is connected to the main body 40of the printer 200 instead of being located in cartridge 31'. Thisarrangement leaves space empty on board 30' and allows for the additionof a RAM chip

70 shown in dashed lines in FIG. 5

to board 30' if additional random access memory is required. Thisarrangement also contributes to a considerable reduction in size ofcartridge 31' as compared to the situation in which a parallel interfaceis located in the cartridge 31.

Reference is next made to FIG. 6 wherein a circuit diagram for theelectrical connection of cartridge 31 to main body 40 is depicted.Before cartridge 31 is connected to main body 40, a transistor 150 is ONand a reset signal 300 is maintained in a low state. Reset signal 300 istransmitted to MPU 7 and the output terminal of MPU 7 is in its high orhigh impedance state. As a result, the output of inverter 201 is low anda transistor 151 is OFF which prevents current flow through coil 202. Inother words, MPU 7 is in its reset position before cartridge 31 isconnected to main body 40.

If cartridge 31 is connected to main body 40 an electric current flowsto ground through cartridge 31. As a result, transistor 150 is turnedOFF and reset signal 300 is high. MPU 7 is released from its resetposition and has a low output. Consequently, the output of inverter 201is high and transistor 151 is turned ON thereby allowing current to flowthrough coil 202.

If cartridge 31 is disconnected from main body 40 during the printingoperation, i.e., when an electric current is being supplied to a coil202 in the print head, reset signal 300 reverts to a low state and theoutput terminals of MPU 7 returns to the high or high impedance state.As a result, the output of inverter 201 is low and transistor 151 isturned OFF. The result is that current can no longer flow throughtransistor 151 to ground and the electric current through coil 202 isprevented from flowing. This protects coil 202 from overheating.

Reference is next made to FIG. 7 wherein a flow chart diagram of theoperation of a printer 200 constructed in accordance with the inventionis depicted. When a power source for the printer 200 is turned ON,control ROM 9 in the cartridge 31 is read by MPU 7 and print headdriving circuit 4, CR motor driving circuit 5, LF motor driving circuit6, MPU 7 and RAM 8 are initialized in accordance with the order storedin ROM 9 as shown in step 1. Next, interface 11 is initialized as shownin step 2 to enable a host computer (not shown) to start thetransmission of command or printing data to the printer 200. The printer200 determines if the information from the host machine 72 is a data ora command transmission (step 3). If the transmission is in the form ofdata, the data is stored in RAM 8 as shown in step 4. Next, the printer200 returns to step 3 to determine what form the next transmission fromthe host machine 72 takes.

If the transmission from the host machine 72 is determined in step 3 tobe a command, the command is accordingly processed in step 5. In step 6a determination is made whether the command is a printing or nonprintingcommand. If the command is a nonprinting command, control returns tostep 3. However, if the command is a printing command, head movement andread out of printing data in step 7 and printing in step 8 commences.

If the printing data, for example, is composed of characters, aspecified character pattern is read out of character ROM 10 and MPU 7controls CR motor 5 to start moving print head 1. When print head 1passes each specified position, print head driving circuit 4 operates tocause printing head 1 to effect printing (step 8).

The various operating steps described are carried out in accordance withthe order contained in control ROM 9. Control ROM 9, character ROM 10and interface 11 are all designed specifically to suit the host machine72 in which the printer 200 is connected. A laser card, or a cardpunched by a laser can be used for each of ROMs 9 and 10. A laser cardcan store a far larger amount of data than a semiconductor memory.

Accordingly, as described above, the specifications of a printer 200 canbe changed to suit a host machine 72 by merely changing a cartridge 31.The main body of the printer 200 is adaptable for use with a widevariety of host computers without any need for a change in theconfiguration or specification of the printer 200. Rather, the onlychange necessary is a removal of one cartridge 31 and the insertion ofanother cartridge 31. This allows for reductions in the cost ofproduction and time for development of a printer 200 suitable for usewith a new host computer. In addition, the necessary changes in thespecifications of a particular printer 200 can be achieved by usingdifferent cartridges 31 for different host computers. The variouscartridges 31 have different print control programs adapted for theprint control systems used by different host machines 72. As a result, aprinter 200 constructed in accordance with the present invention can bemade suitable for a working environment in which a wide variety of hostcomputers are to be connected to a single printer 200. A user couldpurchase a single printer 200 with several cartridges 31 for use withvarious host machines 72.

In addition, increases in efficiency in the production line are achievedby constructing printers 200 in accordance with the invention. A singleproduction line for the main bodies of the printers 200 can be commonfor printers 200 suitable for use with a wide variety of host computers.The only separation in production is in the production of the cartridges31 for use in host computers with different print control systems.

It will thus be seen that the objects set forth above, and those madeapparent from the prceding description, are efficiently attained and,since certain changes may be made in the above constructions withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. A printer comprising:a main body including aprinting head, at least one motor , a plurality of circuits for drivingthe printing head and the at least one motor , processing means and arandom access memory; a cartridge for containing memory means forstoring data associated with at least one character font set and aprinting operation control program and further including interface meansfor connecting the printer to a host machine; and means for removablyconnecting the cartridge mechanically and electrically to the main body;whereby the printing operation control program and character font setscan be selectively set by connecting an appropriate cartridge.
 2. Theprinter of claim 1 wherein the memory means includes at least oneread-only memory device for storing the character font set data andprinting operation control program.
 3. The printer of claim 1 whereinthe memory means includes one read-only memory device for storing thecharacter font set data and a second read-only memory device for storingthe printing operation control program.
 4. The printer of claim 3further including circuit means for selecting one of the two ROMs. 5.The printer of claim 1 wherein the means for removably connecting thecartridge includes a set of male and female connectors, one of the setbeing provided on the cartridge and the other on the main body.
 6. Theprinter of claim 5 wherein the main body includes a cavity adapted toreceive the cartridge therein.
 7. The printer of claim 2 wherein theread-only memory device is a laser card.
 8. The printer of claim 2wherein the read-only memory device for storing character font data andthe read-only memory device for storing the printing operation controlprogram are laser cards.
 9. The printer of claim 1 further including arandom access memory device in the cartridge for providing the printerwith additional random access memory.
 10. The printer of claim 1 whereinthe interface means is a RS232C interface.
 11. The printer of claim 1wherein the memory means includes means for storing the data for aplurality of character font sets.
 12. The printer of claim 1 wherein theprinting head includes a coil and the means for removably connecting thecartridge mechanically and electrically to the main body includes firstcircuit means in the cartridge and second circuit means in the main bodyof the printer for electrically coupling with the first circuit meanswhen the cartridge is coupled to the main body, and for preventingcurrent from flowing through the coil when the cartridge is disconnectedfrom the main body.
 13. The printer of claim 12 wherein the firstcircuit means includes a ground and a connector coupled to ground andsaid second circuit means includes switching means, coupled to theconnector of said first circuit means when the cartridge is connected tothe main body and uncoupled from the first circuit means when thecartridge is removed from the main body, for providing an enabling or adisabling output and coil switch means for allowing current to flowthrough the coil when said enabling output is produced and forpreventing current from flowing in the coil when the disabling output isreduced.
 14. The printer of claim 13 wherein the coil switch meansincludes a transistor having a source and drain path coupled in seriesbetween the coil and ground, a gate electrode of said transistor beingcoupled to the output of said second circuit means.
 15. The printer ofclaim 1 wherein the means for removably connecting the cartridgeincludes a set of male and female connectors, one of the set beingprovided on the cartridge and the other on the main body.
 16. In aprinter including a printing head, a circuit for driving the printinghead, a carriage motor, a circuit for driving a carriage motor, a linefeed motor, a circuit for driving the line feed motor, a microprocessorunit operationally connected to the circuits for driving the printinghead, carriage motor and line feed motor, a character read-only memorydevice operationally connected to the microprocessor unit for specifyinga style of characters , a control read-only memory device operationallyconnected to the microprocessor unit for controlling the printingoperation and an interface for connecting the printer to a host machine,the improvement comprising: a cartridge supporting the control andcharacter read-only memory devices and interface, a main body of theprinter being defined as the printing head, carriage motor, line feedmotor, circuits for driving the printing head, carriage motor and linefeed motor and the microprocessing unit, the cartridge and memorydevices and interface supported thereby being removably coupled to themain body of the printer.
 17. A printer comprising:a main body includinga printing head, at least one motor, a plurality of circuits for drivingthe printing head and the at least one motor, processing means and arandom access memory; a cartridge for containing memory means forstoring data associated with at least one character font set andinterface means for connecting the printer to a host machine; and meansfor removably connecting the cartridge mechanically and electrically tothe main body; whereby the character font sets and interface means canbe selectively set by connecting an appropriate cartridge.
 18. Theprinter of claim 17 wherein the main body further includes a printingoperation control program.
 19. The printer of claim 17 wherein thememory means includes at least one read-only memory device for storingthe character font set data.
 20. The printer of claim 17 furtherincluding a random access memory device in the cartridge for providingthe printer with additional random access memory.
 21. A printercomprising:a main body including a printing head, at least one motor, aplurality of circuits for driving the printing head and the at least onemotor, processing means and a random access memory; a cartridge forcontaining a printing operation control program and interface means forconnecting the printer to a host machine; and means for removablyconnecting the cartridge mechanically and electrically to the main body;whereby the printing operation control program and interface means canbe selectively set by connecting an appropriate cartridge.
 22. Theprinter of claim 21 wherein the main body further includes memory meansfor storing data associated with at least one character font set . 23.The printer of claim 21 wherein the memory means includes at least oneread-only memory device for storing the printing operation controlprogram.
 24. The printer of claim 21 wherein the means for removablyconnecting the cartridge includes a set of male and female connectors,one of the set being provided on the cartridge and the other on the mainbody.
 25. The printer of claim 21 further including a random accessmemory device in the cartridge for providing the printer with additionalrandom access memory.